Electrolysis of aqueous electrolyte solutions



Aug. 20, 1968 w. JUDA 3,398,069

ELEGTROLYSIS OF AQUEOUS ELECTROLYTE SOLUTIONS Original Filed Jan. 9,1961- 2 Sheets-Sheet 1 FIG.I. "f r as 43 52 4Q 38 43 \V////I I V V V vLv C 5 54 BASE ACID FIG. 2.

64 26 MICROPOROUS MACROPOROUS |NVENTOR= WALTER JUDA, BY M ATTORNEY Aug.20, 1968 w. JUDA 3,398,069

ELECTROLYSIS OF AQUEOUS ELECTROLYTE SOLUTIONS Original Filed Jan. 9,1961 2 Sheets-Sheet 2 8O 31E; \\Y///////// /////V///A\\ 82 CV\\\T////////////7////////A\ 7 9o 92 ACID BASE loo FlG.48.6 MICROPOROUSMACROPOROUS &

INVENTOR= WALTER JUDA,

BY i Z; 6

ATTORNEY 3,398,069 ELECTROLYSIS OF AQUEOUS ELECTRDLYTE SOLUTIONS WalterJnda, Lexington, Mass., assignor to Ionics Incorporated, Cambridge,Mass, a corporation of Massachusetts Original application Jan. 9, 1961,Ser. No. 81,334, now Patent No. 3,214,362, dated Oct. 26, 1965. Dividedand this application May 21, 1965, Ser. No. 470,286

2 Claims. (Cl. 20498) This application is a division of Ser. No. 81,334,filed Jan. 9, 1961, now Patent No. 3,214,362.

This invention relates to electrolysis of aqueous electrolyte solutions,and more particularly to the electrolytic conversion of a concentratedsalt solution to an acid and a base, and novel apparatus for performingthe conversion.

It is known that the passage of a direct electrical current ofsufiicient magnitude through an aqueous salt solution between a cathodeand an anode immersed therein results in the electrolytic separation ofthe salt to form a base in the catholyte and an acid in the anolyte whenthe anode and cathode are maintained in separated compartments. Wherethe salt, for instance, is an alkali metal salt, alkali metal hydroxideand an acid are produced, but the anode is subject to chemical attack byoxygen produced therein as a reaction product. This not onlynecessitates frequent replacement of the anode, but results in lowcurrent efficiencies in the operation of the process.

Fuel cells, known in the art, can be characterized as electrochemicaldevices in which a substantial portion of the chemical energy of anoxidation-reduction reaction is converted directly to useful electricalenergy. A typical fuel cell comprises a pair of porous, catalyzedelectrodes separated by an electrolyte, means for introducing a fuel,such as hydrogen into one of the electrodes, and means for introducingan oxidant gas, such as air, into the other of the electrodes. Thereaction of the fuel and oxidant creates electrical energy which is thenavailable at the electrodes.

The use of electrolytic cells for effecting electrochemical conversionswith electrical energy derived, at least in part, from the use of one ormore porous, catalyzed electrodes to which are fed a fuel or oxidant inaccordance with the requirements of the process and the nature of theparticular catalytic electrode, has been disclosed in co-pending US.patent applications, Ser. No. 842,892, filed Sept. 28, 1959, now PatentNo. 3,124,520; and Ser. No. 7,046, filed Feb. 5, 1960, now Patent No.3,103,473. In these disclosures, the anode process, i.e., the ionizationof a fuel supplied to the anode, was employed to produce, by directconversion, part of the energy consumed in the over-all process. Inco-pending US. patent applications, Ser. No. 8,269, filed Feb. 12, 1960,and now abandoned, and Ser. No. 66,498, filed Nov. 1, 1960, now PatentNo. 3,117,066, part of the direct current used for the electrochemicalconversion of certain compounds was produced by the cathode process,i.e., the ionization of an oxidant supplied to the cathode.

Consequently, a principal object of the present invention is to providea novel process for the electrolysis of saline electrolyte solutions toform basic and acidic aqueous products which a considerable saving inthe electrical energy required. Other objects of the present inventionare to provide a novel apparatus for performing the process of theinvention; to provide an apparatus for performing said process which iscompact, produces the base and acid at a substantially reduced cost, issimple to operate, and in which the problems of corrosion by anddisposal of gaseous by-products is substantially less- 31,398,069Patented Aug. 20, 1968 ened, and to provide such an apparatus whichcomprises a novel bipolar electrode. Other objects of the invention willin part be obvious and will in part appear hereinafter. The inventionaccordingly comprises the process involving several steps and therelation and order of one or more of such steps with respect to each ofthe others, and apparatus possessing, the construction, combination ofelements and arrangement of parts which are exemplified in the followingdetailed disclosure, and the scope of the application of which will beindicated in the claims.

For a fuller understanding of the nature and object of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawing in which:

FIGURE 1 is a schematic, side elevational, cross-section diagram of aplurality of cells forming an embodiment of an apparatus of theinvention;

FIGURE 2 is an enlarged diagrammatic cross-sectional View of a bi-polarelectrode element of the embodiment of FIGURE 1;

FIGURE 3 is a schematic, side elevational, cross-section view of aplurality of cells forming another embodiment of an apparatus of theinvention; and

FIGURE 4 is an enlarged cross-sectional view of a bipolar electrode ofthe embodiment of FIGURE 3.

For the purposes of illustration, application of the invention to theelectrolytic conversion of aqueous sodium sulfate is detailed herein.The conversion of sodium sulfate to sulfuric acid and caustic soda hasrecognized commercial significance. In the well-known viscose process,for instance, the digestion of cellulose in caustic soda forms thesodium salt of the former which is then reacted with carbon disulfide toyield a viscous, colloidal, Xanthate sol in dilute aqueous alkali. Afterthe xanthate has been allowed to ripen, the cellulose is regenerated infilament form by precipitation in a solution comprising sulfuric acid,thereby forming sodium sulfate. Thus, caustic soda and sulfuric acid areemployed in large quantities in the viscose industry and the conversionof the waste sodium sulfate back to the original acid and base at areasonable cost is a highly desirable object. Many efforts have beendirected toward converting the sodium sulfate for reuse in the viscoseprocess and some examples of methods heretofore proposed may be found inthe patent literature for example, US. Patent No. 2,273,795, and BritishPatent No. 764,181. In the electrochemical methods heretofore proposed,the costs of the electrolytic conversion of sodium sulfate has beenlargely determined by the amount of electrical energy employed in thecells. In most electrolytic cells for the electrolysis of concentratedsolutions of alkali salts, such as sodium sulfate, the individual cellseach comprise a plurality of compartments defined by one or morepermeable partition or barrier disposed in the inter-electrode space.Such partitions have been in some instances simple porous diaphragrnssuch as in the cell disclosed in US. Patent No. 1,126,627, or they havebeen formed as ion permselective membranes, such as in the celldisclosed in US. Patent No. 2,723,229. Such barriers or permeablepartitions have been included primarily to minimize intermixing of theproducts formed at the electrodes while providing a comparatively freepath for the passage of electrical current from one electrode to theother.

One embodiment of the invention generally comprises a multicellularapparatus such as a plurality of electrolytic cells in linear adjacentarray, the interior of each cell being separated from the interior ofthe next adjacent cell by a unitary, bipolar electrode. Each bipolarelectrode is formed as a unitary element comp-rising an anodic surfaceand a cathodic surface. One end cell of the array includes a cathodewhile the other end cell includes an anode. Thus,

each cell comprises a pair of electrodes, and the array is arranged withthe anode and anodic surfaces and the cathode and cathodic surfacesalternate in sequence so that when the cells are filled with an aqueouselectrolyte, the passage of current between the anode and cathodeevolves hydrogen gas at the cathode and at the cathodic surfaces of thebipolar electrodes. The anode surfaces are formed as electricallyconductive, microporous, catalyzed elements, and the cathodic surfacescomprise electrically conductive, porous means for introducing hydrogengas formed thereat into an associated anodic surface. The gas diffusesfrom the cathodic surface into the anodic surface where it isdissociated into ions by the catalytic action of the latter. Catalystswhich are effective for the purpose involved herein are well known, perse, and may for example be found in the patent to Grubb, No. 2,913,511,column 3, lines 40 et seq. The ions are displaced from the surface ofthe catalyst so as to be driven through the triphase boundary formed byelectrolyte, leaving a current producing electron at the anode for eachion formed. Each cell preferably includes one or more ion-permeablebarriers disposed between the cell electrodes.

Referring now to the drawings, there is shown in FIG- URE 1 anembodiment of an apparatus for performing the process of the inventionand comprising a plurality of three-compartment cells. In the formshown, the apparatus is shown as a two-cell structure comprising a firstsubstantially hollow cell 26 including a positive electrode or anode 22and a negative electrode which, in the form shown, is cathodic surface24 of bipolar electrode 26 described in more detail hereinafter, theanode and cathode surface being in spaced-apart relation to one another.Anode 22 is preferably electrically insulated by known means, such asinsulator 27, from the body of the cell. The interspace between anode 22and cathodic surface 24 is divided by a pair of permeable barriers 28and 30 into anode chamber 32, intermediate chamber 34 and cathodechamber 36. Barriers 28 and 30, in one form of the invention, comprisemacroporous, fluid-permeable diaphragms, formed for instance of porousceramic plates, fiber asbestos cloth or matting, or other materials wellknown in the art and substantially inert with respect to the fluidsintended to permeate therethrough.

In an alternative embodiment, the barriers comprise ion-permselectivemembranes generally formed of a solid, sheet-like, polymeric structurepreferably reinforced by an embedded screen, mat, or the like, andcontaining ion exchange resins fixed in the polymeric matrix. One of thecell membranes, for instance barrier 28, is a film or layer containing acation-exchange resin, well known in the art and examples of which aredescribed in US. Patent Nos. 2,731,408, 2,731,411, etc. A preferred formof cation permselective membranes is one which contains carboxylategroups such as a membrane manufactured by copolymerizing divinyl benzeneand an olefinic carboxylic compound such as an anhydride, ester, or acidchloride of acrylic acid and its derivatives in solution in a suitablesolvent. By saturating the polymerized solid material with water, theanhydride, ester, or acid groupings in the polymeric matrix is invertedto salt or acid forms of carboxylate groups. The presence of an aqueoussolvent phase in the polymerized solid provides a structure which isboth electrically conductive and selectively permeable to eations. Theother ion permselective membrane, for instance barrier 30, is then ananion permselective membrane, well known in the art and examples ofwhich are described in US. Patent Nos. 2,73 0,768, 2,800,445, etc.

The structure of te apparatus also comprises a second substantiallyhollow cell 38 including a negative electrode or cathode 40 and apositive electrode, which, in the form shown, is anodic surface 42 ofbipolar electrode 26. Cathode 40 is preferably electrically insulatedfrom the body of the cell by means, such as insulator 43, known in theart. Cathode 40 and anodic surface 42 are in spaced-apart relation toone another, the interspace between them also being divided by a pair ofpermeable barriers 44 and 46 into an anode chamber 48, intermediatechamber 50 and cathode chamber 52. Barriers 44 and 46 are substantiallyof the same type as barriers 28 and 30, depending of course upon theparticular embodiment of the invention desired. It will be seen that thebarriers within each cell are so disposed that the communication betweenthe chambers formed by the barriers may be had only through the latter.

Anode 22 and cathode 40 are respectively connected to means, such aselectrically conductive leads 54 and 55, for impressing a DC potentialacross the apparatus.

Means are provided for introducing an aqueous solution of a salt intothe intermediate chambers of each cell, and in the form shOWn, thiscomprises a conduit or manifold 56 ported to the intermediate chamber ofeach cell so as to provide a common feed thereto. Means are alsoprovided for removing aqueous effiuent from each anode chamber of eachcell, and in the form shown, the latter means comprises a conduit ormanifold 58 joining all of the anode chambers in common. Similarly,means such as manifold 60 are provided for removing aqueous eiiluentfrom each of the cathode chambers of each cell, manifold 60 beingconnected to the cathode chambers to form a common conduit therefrom.

The individual cells forming the invention may be varied as to size ofthe cell, as to both the size and number of the individual chambers orcompartments in each cell, the form of the means for supplying aqueoussalt solution to the center or intermediate chambers, the means forremoving the aqueous efiiuent from the anode and cathode chambers,valving, and the material from which the cell bodies or enclosures areformed. However, adjacent cells must be separated from one anothersubstantially only by a bipolar electrode common to the two cells. Inthe preferred form, all of the bipolar electrodes (a portion of such anelectrode being shown in enlarged cross-section in FIGURE 2) comprise acathode portion 62 and an anode portion 64 of equal size. Where theelectrode is intended to catalyze a fuel gas, such as hydrogen, theporosity, and therefore the specific surface area of the bipolarelectrode, is graded from the cathode portion to the anode portion, thetwo portions being pneumatically connected to one another. In thepreferred embodiment of a hydrogen catalyzing electrode, cathode portion62 is preferably substantially macroporous, while the anode portion 64preferably is a substantially microporous, catalyzed element having avery high surface area. This may be accomplished, for example, byforming the anode portion of a sintered mat of catalytic, metalmicro-filaments, such as nickel powder activated by platinum, or asponge of platinum, iridium, palladium, rhodium, and other metals chosenfrom Group VIII of the Periodic Table. Cathode portion 62 may be formedof nickel or steel sponge, porous carbon, or the like. The cathodeportion and anode portion are in intimate physical and electroniccontact with one another throughout so as to form an integral unit byany convenient bonding method known in the art which does not interferewith either the pneumatic intercommunication between the portions orwith the ready passage of electrical current from one portion to theother. Means, such as plastic seal 65, formed of a substantiallychemically inert, water and gas impervious material, for instancepolytetrafluorethylene, polyvinyl chloride, and the like, is provided asa continuous strip around the common joined edges of the cathode portionand anode portion to insure that no gas leak can occur at the edges ofthe bipolar electrode.

In the form of the apparatus shown, there is included means, such asmanifold 66 for providing a controlled supply of water to the anode andcathode chambers in order to control the concentration of the productsformed in the latter and to assist in governing the flow of fluidthrough the apparatus.

In keeping with the discussion of the electrolytic conversion of aqueoussodium sulfate set forth hereinbefore, the operation of the inventionwill be described with relation to that process. In operation, asolution of sodium sulfate is fed through manifold 56 to intermediatechambers 34 and 50 of each cell. Where barriers 28', 30, 44, and 46 areporous diaphragms, it is desirable to maintain a steady flow ofelectrolyte into the cells through manifold 56 in order to preventback-migration of the ions. Simultaneously, a stream of Water is fedinto each anode chamber and cathode chamber through manifold 66. When aD.C. electric potential is initially applied to the apparatus at anode22 and cathode 40, the resistance is first comparatively high until theion concentration in the cathode and anode chambers becomes sufiicientto readily conduct the electric current therethrough. This occurs in acomparatively short time interval. The sodium ions and sulfate ions,under the influence of the applied electrical potential, move from thecenter chambers to the respective adjoining cathode and anode chambers,caustic soda being formed in the cathode chambers and sodium acidsulfate being formed in the anode chambers. Along with the production ofthe acid and base, hydrogen gas is formed at the respective cathodeswhile oxygen is produced at the anodes.

It should be noted that the apparatus of FIGURE 1 is preferablyconstructed so that the cells are stacked in a vertical array with thecathode compartment of each cell at the top and the anode compartment ofeach cell at the bottom. Thus, the hydrogen produced at the cathode ofthe lower-most cell of the array tends to rise and, diffusing readilythrough the porous structure of the cathode, permeates the anodicportion of the bipolar electrode separating the lower cell from the nextuppermost cell. The hydrogen gas thus diffused into the anodic portionof the bipolar electrode is dissociated into ions by the catalystcontained in the anodic portion of the bipolar electrode. The ions thusformed are displaced from the surface of the catlayst and are injectedinto the anode chamber wherein they combine with oxygen produced at theanode to form water, thus preventing anode attack by the oxygen. Foreach such ion displaced from the anodic portion, a current producingelectron is released, thereby providing a portion of the electricalpower required for the process. The construction of the bipolarelectrode therefore provides an apparatus Where hydrogen produced at thecathodic portion of each bipolar electrode is employed to contribute tothe over-all electrical power required in the process and substantiallyreduces the effective internal resistance of the apparatus. Of course,because the cathode of the upper-most cell is not necessarily porous nordoes it necessarily form a portion of a bipolar electrode, the hydrogenproduced thereat does not diffuse into an adjacent cell. Instead, means,such as outlet port 68 are provided for venting the hydrogen gas whichmay then be lead to a microporous, catalyzed form of anode 22 throughappropriate duct work or conduit means, or may be disposed of in someother manner. From the respective cathode compartments, a high puritygrade of sodium hydroxide solution is continuously withdrawn throughmanifold 60 while from the respective anode compartments a mixture ofsodium sulfate and sulfuric acid, i.e., sodium acid sulfate, iswithdrawn through manifold 58.

In another embodiment of an apparatus for performing the process of theinvention, shown particularly in FIG- URE 3, the apparatus againcomprises a two-cell structure comprising a first cell 80 including ananode 82 and a negative electrode comprising cathodic surface 84 ofbipolar electrode 86 described hereinafter. The anode and cathodesurface are in spaced-apart relation to one another and, analogously tothe embodiment of FIG- URE 1, the interspace between the electrodes isdivided by a pair of permeable barriers 87 and 88 of the typehereinbefore described into three chambers, one adjacent the anode,another adjacent the cathode, and a third chamber intermediate the firsttwo. The structure also comprises a second cell 90 including a cathode92 and a positive electrode comprising anodic surface 94 of the bipolarelectrode, the latter forming an element which separates the cells onfrom the other. The interspace between the electrodes of cell 90 arealso divided by a pair of permeable barriers 96 and 98 into threechambers. It should be noted that the apparatus, as is the apparatus ofFIGURE 1, is preferably constructed so that the cells are stacked in avertical array, but in this embodiment the anode chamber of each cell isat the top-most portion thereof while the cathode chamber of each cellis at the bottom.

Bipolar electrode 86, which separates the two cells, and a portion ofwhich is shown in enlarged cross-section in FIGURE 4, comprises acathode portion 100 and an anode portion 102 of substantially equalsize. Because the bipolar electrode in this embodiment is intended tocatalyze an oxidant gas, such as oxygen, the porosity and therefore thespecific surface area of the electrode is graded from the anode portionto the cathode portion, the two portions, being pneumatically connectedand in intimate physical and electronic contact with one another. In thepreferred embodiment of an oxygen catalyzing bipolar electrode, anodeportion 102 is preferably a substantially macroporous body, whilecathode portion 100 preferably is a substantially microporous, catalyzedelement having a very high surface area. Cathode portion 100 is formed,for example, of microporous carbon catalyzed with silver, gold or othernoble metals, or as a microporous silver element. Anode portion 102 inturn is formed, for instance, of steel sponge or macroporous carbon orthe like. In all other respects, bipolar electrode 86 is formedsimilarly to the bipolar electrode heretofore discussed in connectionwith FIGURE 2.

In operation, the electrolysis of a saline solution introduced into thesaid compartments through appropriate conduit means is quite similar tothe operation of the apparatus of FIGURE 1 heretofore described. Theions of the dissociated salt, under the influence of applied electricalpotential, move from the intermediate chambers through the adjoiningion-permeable barriers to the respective adjoining cathode chamber andanode chamber, a base being formed in the former and an acid beingformed in the latter. Simultaneously, oxygen gas is produced at therespective anodes while hydrogen gas is formed at the respectivecathodes. Because of the vertical construction of the cell, the oxygenproduced at the anode of the lower-most cell tends to rise and diffusereadily through the porous structure of the anodic portion permeatinginto the cathodic portion of the bipolar electrodes separating the lowercell from the next adjacent cell. The oxygen gas thus fed into thecathodic portion of the bipolar electrode is dissociated into ions bythe catalyst contained in the latter and the ions are injected into thecathode chamber wherein they combine with the hydrogen produced at thecathode to form water. For each such ion displaced from the cathodicportion, a current producing electron is released, thereby providing aportion of the electrical power in a manner similar to that heretoforedescribed.

The apparatus herein disclosed for performing the process of theinvention is useful for many processes. For instance, the apparatus ofFIGURE 1 is useful for performing a dual process at the cost ofelectrical power ordinarily required for but one of the processes.Referring to FIGURE 1, a similar apparatus thereto is used whereinpermeable barriers 28, 30, 44 and 46 are removed. Into cell 38 there isintroduced a solution of CuSO this cell being provided with a cathode 40upon which Cu is intended to plate out and therefore can be formed ofmany electrically conductive materials such as Cu, Fe, Ni and the like.Cell 20 is provided with an anode, such as graphite. Into cell 20 thereis introduced a solution of NaCl. Upon impressing a DC potential acrossthe two cells, Cu will plate out in cell 38 and the cell eflluent willcontain H 80 contaminated with CuSO in varying degrees according to thecell voltage, the concentration and flow rate of the infiowing CuSOsolution and the size of the cathode relative to the instantaneousconcentration of CuSO Simultaneously, the NaCl solution is electrolyzedto produce NaOCl as the effluent of cell 20. By inserting a porousdiaphragm between the anode and cathodic surface in cell 20 and flowingthe NaCl into the interspace between the anode and the diaphragm, thecell will produce NaOH with the evolution of C1 at the anode. As withthe embodiment heretofore described in connection with FIGURE 1, thehydrogen evolved at cathodic surface 24 produces electrical power sothat the voltage drop across the bipolar electrode is negligible. Hence,it will be apparent that several useful products, H 80 and eithercaustic soda, chlorine or NaOCl are produced with the electrowinning ofcopper with large savings of electrical energy.

By replacing the CuSO solution with FeSO it will be immediately apparentthat the same structure can be employed to produce both NaOCl (or NaOHand Cl) and plate out iron instead of copper. In this latter process, itis preferred to introduce a porous diaphragm or cation exchange membraneto separate the cathode of cell 38 from anodic surface 42 of the bipolarelectrode and flow the FeSO solution into the interspace between thediaphragm and cathode. This maintains the solution pH adjacent thecathode at a relatively high level and minimizes attack by the resultingacid upon the plated-out metal.

Since certain changes may be made in the above process and apparatuswithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description as shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:

1. A process for the electrolysis of an aqueous saline electrolytecomprising the steps of introducing said aqueous electrolyte into amulticellular device wherein the cells are separated by electricallyconductive, porous elements each of which constitutes one electrode ofeach of adjacent separated cells, impressing an electrical current uponsaid device between a pair of terminal electrodes thereof therebyforming a basic solution and hydrogen gas adjacent negative electrodesand an acidic solution and oxygen gas adjacent positive electrodes,diffusing one of said gases through the electrodes adjacent thereto andinto the electrode of opposite polarity of the next adjacent cell,catalyzing said one of said gases in said electrode of opposite polarityto form ions of said one of said gases thereby contributing a portion ofthe electrical power required for the electrolysis, combining said ionswith the other of said gases adjacent said electrode of oppositepolarity thereby disposing of the other of said gases, withdrawing saidbasic solution from adjacent said negative electrodes, and withdrawingsaid acidic solution from adjacent said positive electrodes.

2. A process for the electrolysis of aqueous saline electrolytes asdefined in claim 1 including the steps of segregating said acidic andbasic solutions from one another and from said electrolyte by permeablebarriers.

References Cited UNITED STATES PATENTS 2,767,135 10/ 1956 Juda et al20493 2,681,884 6/1954 Butler 20498 2,829,095 4/ 1958 Oda et al 204-982,955,999 10/ 1960 Tirrell -1 204-180 2,969,315 1/1961 Bacon 204-2843,080,304 3/1963 Andous 204l29 3,282,834 11/1966 Justi et a1. 204180FOREIGN PATENTS 973,810 10/ 1964 Great Britain.

JOHN H. MACK, Primary Examiner.

D. R. JORDAN, Assistant Examiner.

1. A PROCESS FOR THE ELECTROLYSIS OF AN AQUEOUS SALINE ELECTROLYTECOMPRISING THE STEPS OF INTRODUCING SAID AQUEOUS ELECTROLYTE INTO AMULTICELLULAR DEVICE WHEREIN THE CELLS ARE SEPARATED BY ELECTRICALLYCONDUCTIVE, POROUS ELEMENTS EACH OF WHICH CONSTITUTES ONE ELECTRODE OFEACH OF ADJACENT SEPARATED CELLS, IMPRESSING AN ELECTRICAL CURRENT UPONSAID DEVICE BETWEEN A PAIR OF TERMINAL ELECTRODES THEREOF THEREBYFORMING A BASIC SOLUTION AND HYDROGEN GAS ADJACENT NEGATIVE ELECTRODESAND AN ACIDIC SOLUTION AND OXYGEN GAS ADJACENT POSITIVE ELECTRODES,DIFFUSING ONE OF SAID GASES THROUGH THE ELECTRODES ADJACENT THERETO ANDINTO THE ELECTRODE OF OPPOSITE POLARITY OF THE NEXT ADJACENT CELL,CATALYZING SAID ONE OF SAID GASES IN SAID ELECTRODE OF OPPOSITE POLARITYTO FORM IONS OF SAID ONE OF SAID GASES THERBY CONTRIBUTING A PORTION OFTHE ELECTRICAL POWER RE-